Rpi4 forced into 4:3 ratio when connected to vga port

Hello, guys.

I have a really old Toshiba 37WL66C TV (probably 12 yrs old or more) and a newlly bought Raspberry Pi 4 with latest version LibreELEC installed.

My TV has a 16:9 screen up to 1366*768 resolution, along with a hdmi port and a vga port. I tested Rpi on hdmi port and it works fine. Since the only hdmi port is constantly occupied by other device, I would like to use vga port instead.

The problem is, when connected to vga port, Rpi was forced into a 4:3 ratio 1024*768 resolution, and nowhere in Kodi menu to change it to 1366*768 or any 16:9 ratio resolution.

One reason I can think of is that the Toshiba TV has a PC mode, when connected through vga port, it automatically switch into PC mode (which is confirmed by TV userguidebook), and when the TV was initially designed, all PC monitors were supposed to have 4:3 display ratio, so the TV just keep telling Rpi I' m a PC, give me 1024*768.

Please, IS there any way to manually add 1366*768 resolution into system, so that it can be selected and remembered by Kodi?

(Just in case anyone wonder, I use a lenovo micro hdmi to vga adapter on Rpi, and it works perfectly when connected to Acer 1440*900 monitor, no resolution problems.)

Thanks for the reply.

I also tested the vga port with my PC, which has a Intel GPU inside. It turns out my TV can receive 1366*768 signal without switch into PC mode. As long as I select 1366*768 resolution from Intel configuration, the TV automatically turned off PC mode. I don't know how it works though.